I also have this same issue on the same model TV LN-T5265. I have one, very thin, purple vertical line about 1" from the left side of the screen. It comes and goes and has been showing up for about a month now. It doesn't seem to be any of the other components (DirectTV HD DVR, PS3) as the line has been present and absent using both components. TV is out of original warranty, but I bought a three extended (through Circuit City of course) that is valid until March 2011.
Anyone have any solutions or possible causes?
My Samsung 52" LCD TV LN-T5265f is 18 months old. When first powered on, two thin vertical lines appear toward the left of the screen. After about 20 minutes one line disappears and the remaining one goes spontaneously after a total of 35 mins power on. The time taking to disappear is getting longer so I assume they will be there permanently soon.